Hematology Basics & Hematopoiesis
HEMATOLOGY
What is it?
Encompasses: Skill, Art, Instinct
Relationships
BM:circulation
Plasma:RBC
Hgb:RBC
What Will I Learn?
Students find Hematology difficult because it requires you to think in a new way.
Begin with limited knowledge: Given Facts and you must be able to answer “WHY”
Given images and you must be able to recognize and classify
This Course
Hematology I – MLTS 207
Intro
Red Cells
Hematology II – MLTS 208
White Cells
Coagulation
Our Tool
Safety First
Standard Precautions
PPE
Hand washing
Proper disposal
Proper cleaning
Know what to do in case of an emergency
Fire
Spill
Needle stick
QA vs QC
Quality Assurance
Comprehensive
Preanalytical – Analytical - Post-analytical
Ensures reliable patient results = positive outcome
Quality Control is Analytical only – focuses on actual measurement of the analyte
Quality Control
Standards / Calibrators
Controls
Statistical quality control system
Normals
AKA Reference ranges
Plt 150 – 450 X 103/ul
Unique to analyte, method, instrument and patient population
Delta Check
Critical Values
Blood Basics
Average blood volume 4 – 6 liters
Blood pH = 7.35 – 7.45
Components of whole blood
55% plasma - 44% RBCs - 1% WBCs and platelets (buffy coat)
Red Blood Cell (Erythrocyte or RBC)
White Blood Cell (Leukocyte or WBC)
Platelets (Thrombocyte)
Plasma is 91.5% water and 8.5% solutes
Reference Ranges (patient normals)
RBC 4.2 – 5.4 X 1012/L (106/ul) females
4.7 – 6.1 X 1012/L (106/ul) males
WBC 5 – 10 X 109/L (103/ul)
Platelets 150 – 450 X 109/L (103/ul)
Blood Smears (Slides)
Cells evaluated in an area where red cells are almost touching but do not overlap
Smears can be made by hand or mechanically
Smears are stained with Wright’s stain
Smear is examined on 100X using oil to evaluate RBC morphology
RBC Morphology
Red cells are biconcave disk that are 7 – 8 um in diameter with a volume - 90fL (femtoliters)
When stained they appear as:
Circular cells with distinct smooth margins
Dull pinkish hue
Area of central pallor
Fairly uniform in size
No nucleus or inclusions
Platelet Morphology
Platelets are 2 – 4um in diameter and discoid shaped they contain reddish-purple granules in a small amount of bluish cytoplasm and have no nucleus
Leukocytes
Segmented neutrophils - AKA segs or PMN
Band neutrophils
Eosinophils
Basophils
Lymphocytes
Monocytes
Hematopoiesis
Definition?
Daily Production Quotas
RBCs – 3 billion
WBCs – 1.5 billion
Plts – 2.5 billion
Your body can:
Constantly supply mature blood cells for circulation
Mobilize Bone Marrow to increase production of a particular type of blood cell
Compensate for decreased hematopoiesis by providing hematopoietic sites outside the BM
The Beginning
All blood cells are the progeny of hematopoietic pluriopotential stem cell
In adults these are found in the bone marrow. Why?
Monophyletic Theory
A common precursor cell, the pluripotential stem cell, which under the influence of certain factors gives rise to each of the principle blood cell lines
Cytokines -
Pretty much universally accepted today based on clinical and experimental evidence and started with mice in 1961
Based on this theory, hematopoietic cells may be divided into 3 cellular catagories dependant on maturity
1 Multipotential stem cell able to self-renew and to differentiate into all blood cell lines
2 Committed progenitor cell destined to develop into distinct cell lines
3 Mature cells with specialized functions which have lost the capability to proliferate
Hematopoietic Stem Cell
Most important characteristic – must self renew
Ability to differentiate into commited progenitor cells of lymphoid or myloid lineages
Maturation Process (p.20)
Hematopoiesis From Coception to Adulthood (p.16)
Yolk Sac (embryonic hemoglobin)
Begins 2 -3 weeks after fertilization and ceases after 8 – 10 weeks
Fetal Liver (fetal hemoglobin)
Production from about 2 – 7 months
Liver is main site but spleen, thymus, lymph nodes, and kidney are also involved
Bone Marrow – called medullary hematopoiesis
Begins to function in 3rd month of gestation
Primary site by the end of 5th month of gestation and continues after birth and throughout adulthood
Children distal long bones
Adults axial bones
Extramedullary Hematopoiesis is hematopoiesis outside bone marrow
Not a normal occurrence after 5th month of gestation
Happens in certain disorders
Occurs in liver and spleen
Erythropoiesis
Definition?
Mature erythrocytes carry oxygen from the lungs to tissue where it is exchanged for CO2
Erythropoietin (a cytokine)
Hormone produced by the kidney
Stimulates red cell production
Secreted daily in small amounts
Kidney will sense hypoxia and secrete more if needed
What happens when more EPO is secreted by the kidneys?
Development of Red Cell
Reduction in cell volume
Condensation of chromatin (Loss of nucleoli)
Decrease in N:C ratio (less nucleus – more cytoplasm)
Decrease of RNA in cytoplasm Increased hemoglobin synthesis – to a point
cell turns from blue to red
Developmental Stages (images p33 - 35)
Rubriblast (Pronormoblast)
Each produces 8 – 16 mature red cells
Stage where hemoglobin synthesis begins
Prorubricyte (Basophilic Normoblast)
Rubricyte (Polychromatophilic Normoblast)
Last stage capable of division
Large amounts of hemoglobin synthesized at this stage
Metarubricyte (Orthochroimatophilic Normoblast)
Nucleated Red Blood Cell (NRBC) seen on peripheral smear
Reticulocyte (Polychromatophilic Erythrocyte)
Non-nucleated (nucleus extruded)
Contains residual RNA and mitochondria which gives cell bluish tinge with Wright’s stain
Last stage to synthesize hemoglobin
Part of this phase occurs in the bone marrow, later part takes place in circulating blood
Mature Erythrocyte
Stains pink because of large amount of hemoglobin
No RNA or mitochondria = no synthesizing of proteins or lipids
Normal lifespan 120 days
Have You Seen Your Spleen
Fist shaped organ located on the left side under the rib cage
Blood filled organ consisting of
Red pulp – red cell filtration
Cull old or abnormal RBCs (Reticuloedothelial System)
Pit RBC inclusions
Remove Antibodies - spherocytes
White pulp – lymphocyte processing
Marginal zone – WBC & Plt storage
1/3 population of each
Bone Marrow not Bowel Movement
One of the largest organs in the body
Inside you find erythroid cells, myloid cells, and megakaryocytes in various stages of development – stem cells, fatty tissue, osteoclasts, etc.
As you age marrow in long bones is replaced by fat
Adult marrow in iliac crest and sternum.
M:E ratio -Myeloid to erythroid ratio
Normally 3-4:1
Why are there more myloid cells in the bone marrow and more RBCs in circulation?
Updated 72d ago